Do not take everone’s word for what light output they claim, you can take most lumen claims around with a grain of salt, 20/30% off is really common. That is because measuring light output (lumens) accurately is not trivial , it is hard, lots of parameters need controlled very tightly and people do not realise that.
With a simple home-made contraption and some flashlights with manufacturer-listed output people get ballpark numbers within 20/30%, several people on BLF have made that and it is really what most people, even hobbyists, are happy with. Some BLF-members I trust to be a bit more accurate because they have checked calibration light sources, they may be within 15% (i.e. me, and I know Marco from 1lumen has checked light sources too, and some others)
But to get within that last 5% accuracy is either very expensive (for many thousands of dollars you buy an official integrating sphere plus spectrometer and calibration light sources, and learn how to operate the setup correctly, BLF-member maukka did that) or if you brew a device yourself which is surprisingly difficult to get accurate, you need a very controlled setup (directionally insensitive light collecting geometry, spectrally neutral reflectivities, spectrally correct luxmeters, correctly calibrated light sources) that almost no-one manages to get really right (that official setup is expensive for a reason). People often think they did a good job but end up with 20% variation from the real output easily, because of a flawed setup/wrong operation/dubious calibration sources.
I also do not not think that Hank (Emisar/Noctigon) or Simon (Convoy) have very exact lumen measurents. Maybe Sofirn.